Furnace



Dec.v 7, 1943. w. w. oNEAl. ET AL 2,335,877

' FURNACE Filed Jan. 1'7, 1942 3 Sheets-Sheet 2 Patented Dec. 7, 1943 1 FURNACE Wilbum yW. ONeal and Robert DfWilliamS, f Memphis, Tenn.

r.Applicatien =January.-,17, 1942, Serial No. .427,102

.This invention relates to improvements in furnaces forheating -air,=and particularly-to such furnaces forzheating. air under-.pressure for use irl-.drying leguminous products, -grains Yandy other materials requiring relative large'nuanttiesf'and sharp reductionl in. temperature, off suchair, relatively tothe combustion:quantitiesY and tempera'- turesA of. thevv furnace. p

The objects ofthe. invention-l :are

ATo make a furnace -..capa-ble fof 'withstanding internal.pressureandgadaptedto :receive fand Edischarge-airlfor.combustion-andra Amajor flow of air for drying to l hea-ted f' :directly by, l and by mixing with the'. combustion .products of, said furnace.

ZTo; .provide .meansinrsuchz .ai furnacel for utilizing the drying air for cooling the-Ifurnacewalls pri-orto mixingvwith'the products uof combustion, whereby toraise-t'he temperature of the drying air .fbydirect radiation from the furnace f chamber walls, lprior [to rmiXi-ngit vWithfthe ,iproductsof combustion and thereby-'establishing anual-discharge temperature.

y'Io- .provi-de. means for furnishing drying `air f to said furnace andfor by-passingfizcombustion.-air

toa fuel .burner for-such furnace adaptingk said burner to function against :the internal fpressures set .upf in the furnace.

'Il-he means byffwhichfthe:foregoing .and other objects areaccomplishedand the'method-off their accomplishment willf'readily :be understood from the .following speciflcationuponz-'reference=to'the accompanying drawings, in which:

Fig. 1 is a vertical Lsectional"eletationion the .longitudinal centengline oft-the Ifurnace.

Fig. 3 is a side elevation of the'furnace-*anidf air supply pipes therefor.

Fig. 24 isla corresponding; end elevation.

'.Fig. `5 is an-enlarged end elevation of the burner show-ing the "fuelsupply and "direct :air pipe'lea'ding thereto; and

Fig. '6 "a Fide elevation on the same scale showing the fuel supply pipes, the direct airpipe and air auxiliary air pipe to the burner.

Referring now tothe drawings. in which the various parts-are indicated by numerals:

The furnace comprises a sealed shell, preferably as-of sheet steel, of weightsuc-ient-tostand desired internal pressures to ,be created and maintained within the furnace .by .airpressura the shell comprising front fand. rear .endl walls I II I I-..A, a bottom wall; I3 side walls. I5, and atop wall or arch I'I. -The -shell hasvair inlet land discharge ues I 9 -and..2 I forl drying-air, respectively -leadingrthereinto and therefrom through openings spaced .apart in the rear end walls II-A, and an opening-23 through `the opposite end- Wall -II the opening lbeing adapted to be closedand sealed against-air escapeby Va fuel burner l'25 Ywhich is supplied with injection vand direct` combustion air through an auxiliary pipe 21,.which leads from -afby-.pass pipei'29 connecting thel inlet flue. I9 with the front of the shell below the` burner, for-v the introduction of auxiliary combustionair into the combustion chamber.

rDisposedwithin the furnace shell is'a combustion chamber-3I :enclosed `by front and rear end nwalls 33, .33-A,=side walls '31, -a bottcm.-35, anda top fare-m35, -all of refractorymaterial such as Afire lbrick. The-walls of thecharnber are spaced from.-theshellto provide asurroun'ding airl space, the-:end andside walls' ybeing centered by projecting l .bricks v.cr struts -4 I preferably' at regular .intervalsand-the bott-om supportedin similar spaced'relatien tto the shell by bricks, preferably-in rows 43, disposed to form channel- Ways .extend-ingr from end to end aand-'connecting into ther open-.spaees'at'l-such ends. The cham-ber arch-3d` extendsI from the chamber front end wall 33-to andpast thefchamber rear4 end wall S3-"A and into lcloselyabutting relation withI the rear end shell --wall fI.-I-.A, `sealing off 'the entrance iiue .'IS--and 'therear-.endwall space below the arch fromthe discharge flue 2l. The arch39 is spaced:well.belowtheshell-arch II, which prefer-y ablyfisA `linedwith :refractory Amaterial 45, as 'fire brick, .the .atWo-arfches :coming together along the sides fthezfurnace to seal cffa Imixing chamber 4'Iffrom lwhichfthe#discharge fluey 2 I` leads from the 'side wallcispaces 1 vt-herebelow. This chamber 4'Iisin directcornmunication, at the front end of the urnace,"fwith"thespace'between the furnace walls-33aaiidI the .s'hellf I I, andthrough this space isii-n'drecticornrnunication;'by means of the rear endr-anid side .fw'all' spaces, with the inlet flue t9. TheA archi=-39ris;provided with numerous openings 49 through which direct communication is maintained .between thefurnace chamber 3l and the mixing chamberfill 'I.

The:inletiandoutlet'flues I9v and 2| are connectedbyL-a by-pass pipe-"5I which is'normally closedtbya yal-Vei'53, here indicated as a slide, which;l may 'beipartiallyor fully withdrawnto establish partial or completefby-pass lhow between i= the lin-let `l`and outlet fines should vit be found advisable to reduce temperature of the drying air temporarily or otherwise.

55 is a pressure blower, driven as by an electric motor 51 for furnishing the drying and combustion air, this blower being connected through the inlet ue I9 with the chamber shell and through the by-pas's pipe 29 from this flue into the lower portion of the combustion chamber, and also through the auxiliary pipe 21 leading from this by-pass pipe directly to the burner 25. Flow through the by-pass pipe to the furnace is regulated as by a butteriiy valve 59, and through the auxiliary pipe 21 as by a similar valve 6|.

The burner is mounted on a hinge G3, the.v

pipe 21, in Fig. 6, being shown disconnected from the portion 21-A leading into the burner to permit movement around the hinge. Connection of the pipe portions is established during operation by a sleeve 21--B which is moved up to cover the junction between the pipes and tightened. Fuel for the burner is furnished from a suitable source of supply through a pipe 65 leading into one of the hinge members, a pipe 51, a pump 69 and suitable piping and valves into the burner, the valves including a regulating valve 1|, exteriorly indicatedonly. v,

13 is a lever adapted to be manually shifted and set to desired position along an arc 15, the lever being connected through suitable linkage, including a rod 11 to a bell crank lever 19, and through one arm of this lever operatively to the butterly air valve 6|, the opposite arm of the lever 19 being connected through a rod 8| and arm 33 with the fuel regulating valve 1|. Air and fuel oil are discharged from the burner 25 through a nozzle 25-A directly into the furnace chamber through the opening 23 and for initial combustion this air is augmented by air flowing through the space between the front shell and the front end 33 of the combustion chamber, this air having access through openings 85 to the outside of the nozzle 25-A and discharging along the outside of such nozzle, also through the opening 23 into the combustion chamber. Additional air for combustion is furnished directly into the combustion chamber 3| through the bypass pipe 29 and regulated by the valve 59. The products of the combustion in the chamber 3| heat up the walls of the chamber, and escape through the openings 49 in the arch 39 into the mixing chamber 41. Air entering through the ue |9 passes downward through the space between the rear chamber wall 33-A and the rear shell ||A; thence forward between the corresponding side and bottom passageways and upward through the front end space into the mixing chamber 41 where it mixes with the highly heated combustion gases from the furnace chamber 3|. In its passage around the combustion chamber the entering air cools the chamber walls and is itself raised in temperature by the heat absorbed from the walls before reaching the mixing chamber 41. In the mixing chamber it tempers the highly heated gases of combustion and mixed with these gases is discharged through the flue 2|.

It will be understood that the proportion of the air used for combustion, and that used for mixing with the products of combustion and absorbing and tempering the heat of combustion, may be largely varied, but that it is presently contemplated, as indicated by the relation of the sizes of the flue I9 and the pipe 29, that the tempering air will be greatlyin excess of the combustion air and that the resulting drying air discharged through the flue 2| will be greatly reduced in temperature from the temperature set up in the furnace chamber.

In certain drying operations, such as are disclosed in my pending application, Serial No. 374,212, it is contemplated that the temperature of combustion in the furnace chamber will be around two thousand degrees, whereas the temperature of the drier gases will be of the nature of eight hundred degrees.

We claim:

1. An air heating furnace comprising a shell adapted to withstand internal pressures, a combustion chamber, having enclosing walls including a roof, disposed within said shell and spaced from said shell to provide air spaces substantially completely surrounding said chamber, said space above said roof being enlarged relatively to the other said spaces to form a mixing chamber, said combustion chamber roof extending, at its side edges and one end only, into contact with the sides and one end of said shell to separate said surrounding space, along said end and said sides from said space above said roof, and said roof being honeycombed to establish communication between said combustion and mixing chambers; a fuel burner mounted on the opposite end of said shell and discharging through the adjacent wall of said combustion chamber into said chamber; means for establishing a flow of air under pressure, an inlet flue connecting said pressure flow establishing means into the first named end of said shell and said chamber-surrounding space below said roof, and a discharge flue leading from the same end of said shell and said mixing chamber.

2. An air heating furnace comprising an enclosing shell adapted to withstand internal pressures, a combustion chamber, having enclosing walls, disposed within said shell and spaced therefrom to provide connecting air spaces substantially completely surrounding said chamber, said chamber walls including a top wall honeycombed to establish communication between said chamber and the air space thereabove, means extending along the rear end and sides of said shell and chamber separating said air space above said chamber along said end and said sides from the lower said air spaces, burner means and fuel feed means therefor, mounted on the front end of said shell and discharging through the front wall'of said combustion chamber into said chamber; means for establishing a flow of air under pressure, means connecting said flow establishing means into the rear end of said shell below said dividing means, and a discharge flue leading from the rear end of said shell above said dividing means.

3. An air heating furnace comprising an enclosing shell adapted to withstand internal pressures, walls within said shell enclosing a combustion chamber, said walls being spaced from said shell to provide an air space substantially completely surrounding said chamber, the space between the top wall of said chamber and said shell being greatly enlarged relatively to other portions of said air space to establish a mixing compartment, the said top wall of said chamber being apertured to establish communication with said mixing compartment, means dividing said air space along the rear end and sides of said shell and chamber into upper and lower spaces, burner means and fuel feed means therefor mounted on the front end of said shell and discharging through the front wall of said combustion chamber into said chamber; means for establishing a flow of air under pressure, means connecting said low establishing means through the rear end of said shell into said air space below said dividing means, and a discharge flue leading through the rear end of said shell from said mixing compartment.

4. An air heating furnace including a combustion chamber, having enclosing walls including a roof, means establishing a mixing chamber above said roof, said roof being honeycombed to establish communication between said chambers, fuel burner means having fuel feed means, mounted on and discharging through a wall of said combustion chamber into said combustion chamber, means for establishing a flow of air under pressure, means connecting said pressure flow establishing means into said mixing chamber, and a discharge flue leading therefrom; by-pass means establishing communication between said air flow establishing means and said combustion chamber, and auxiliary means connecting said air flow establishing means with said burner means to establish injection flow of air through said burner means into said combustion chamber.

5. An air heating furnace comprising an enclosing shell adapted to withstand internal pressures, a combustion chamber having enclosing Walls, disposed within said shell and spaced belOW the top of said shell to provide a mixing chamber, said combustion chamber walls including a top Wall, apertured to establish communication with said mixing chamber, burner means and fuel feed means therefor mounted on a wall of said shell and discharging through an adjacent wall of said combustion chamber into said combustion chamber; means for establishing a iiow of air under pressure, means connecting said flow establishing means to said mixing chamber to establish a traversing flow of air therethrough, a discharge nue leading from said mixing chamber, by-pass means establishing communication between said flow establishing means and said combustion chamber, and auxiliary by-pass means connecting said ow establishing means with said burner means to establish injection fiow of air therethrough.

6. An air heating furnace including a combustion chamber, having enclosing walls including a roof, means including said roof establishing an air chamber above said roof, said roof being honeycombed to establish communication between said chambers, fuel burner means having fuel feed means mounted on said chamber and discharging thereinto, means for establishing a ow of air under pressure, an inlet flue connecting said air flow means into said air chamber, and a discharge flue leading therefrom; by-pass means establishing communication between said inlet flue and said combustion chamber, and auxiliary means connecting said by-pass means with said burner means to establish injection ow of air through said burner means into said combustion chamber.

'7. An air heating furnace including a combustion chamber, having enclosing walls including a roof, means including said roof establishing an air chamber above said roof, said roof being honeycombed to establish communication between said chambers, fuel burner means having fuel feed means mounted on said chamber and discharging thereinto, means for establishing a iiow of air under pressure, means connecting said pressure vflow establishing means into said air chamber,

and a discharge flue leading from said chamber; by-pass means establishing communication between said flow establishing means and said combustion chamber, and auxiliary means establishing communication between said flow establishing means and said burner means to establish injection flow of air through said burner means into said combustion chamber.

WILBURN W. ONEAL. ROBERT D. WILLIAMS. 

